Patent application title: INFUSION STATUS INDICATOR

Abstract:

An infusion status indicator disposed in the medical infusion line
includes a housing with an opening through which the status of the
infusion may be determined. A flexible membrane is located at the opening
to indicate the status of fluid in the cavity. A recessed flexible
membrane indicates insufficient flow of medical fluid into the cavity
from the fluid supply, a level flexible membrane indicates correct flow
of fluid through the indicator, and a concave flexible membrane indicates
an insufficient flow of medical fluid out of the cavity, possibly
indicating an occlusion of the fluid line downstream of the indicator.
Check valves may be included upstream and downstream of the cavity so
that a bolus of fluid may be forced out of the cavity to the patient by
pressing the flexible membrane into the cavity.

Claims:

1. An indicator device for indicating the status of medical fluid flow
through an infusion line, the indicator device comprising:a housing
surrounding a cavity through which the fluid may flow, the housing having
a fluid inlet adapted to be coupled to a portion of the infusion line
from which fluid would flow into the housing, a fluid outlet adapted to
be coupled to a portion of the infusion line into which fluid would flow
out of the housing, and an indicator opening; anda flexible membrane
disposed at the indicator opening in contact with fluid in the cavity,
the flexible membrane having a moveable membrane portion configured to
move in relation to the opening in response to pressure of fluid in the
cavity to provide distinguishable cues of the fluid flow status through
the infusion line.

2. The indicator device of claim 1, further comprising:an inlet flow
restrictor disposed in the portion of the fluid line from which the fluid
flows into the cavity, the inlet flow restrictor providing a first flow
resistance to flow of medical fluid into the cavity.

3. The indicator device of claim 2, further comprising:an outlet flow
restrictor disposed in the portion of the fluid line into which the fluid
flows out of the cavity, the outlet flow restrictor providing a second
flow resistance to flow of medical fluid out of the cavity.

4. The indicator device of claim 3, wherein the second flow resistance is
greater than the first flow resistance.

5. The indicator device of claim 2, wherein the inlet flow restrictor is
formed as part of the housing.

6. The indicator device of claim 3, wherein the outlet flow restrictor is
formed as part of the housing.

7. The indicator device of claim 1, further comprising:an outlet flow
restrictor disposed in the portion of the fluid line into which the fluid
flows out of the cavity, the outlet flow restrictor providing a second
flow resistance to flow of medical fluid out of the cavity.

8. The indicator device of claim 1, wherein the moveable membrane portion
is configured to recess into the cavity when the flow rate of fluid
through the cavity is at a first threshold.

9. The indicator device of claim 8, wherein the moveable membrane portion
is configured to extend approximately level with the opening of the
housing when the flow rate of fluid through the cavity is at a second
threshold.

10. The indicator device of claim 9, wherein the moveable membrane portion
is configured to protrude outwardly from the opening of the housing when
the flow rate of fluid through the cavity is at a third threshold.

11. The indicator device of claim 10, wherein the second threshold is
greater than the first threshold and the third threshold is greater than
both the first threshold and the second threshold.

12. The indicator device of claim 1, wherein the moveable membrane portion
is configured to extend approximately level with the opening of the
housing when the flow rate of fluid through the cavity is at a second
threshold.

13. The indicator device of claim 1, wherein the moveable membrane portion
is configured to protrude outwardly from the opening of the housing when
the flow rate of fluid through the cavity is at a third threshold.

14. The indicator device of claim 1, further comprising:a position
indicator disposed on the moveable membrane portion, the position
indicator configured to provide a visual indication of the position of
the moveable portion in respect to the opening to more clearly visually
indicate the status of fluid flow through the fluid line.

15. The indicator device of claim 1, further comprising:a position
indicator disposed on the moveable membrane portion, the position
indicator configured to provide a tactile indication of the position of
the moveable portion in respect to the opening to indicate the status of
fluid flow through the fluid line.

16. The indicator device of claim 1, wherein the movable membrane portion
is configured to have a first position, a second position, and a third
position, such that the moveable membrane portion is located in the first
position when fluid in the cavity has a first predefined fluid pressure
that represents that the flow rate of fluid into the cavity is
insufficient, the movable membrane portion is located in the second
position when fluid in the cavity has a second predefined fluid pressure
greater than the first predefined fluid pressure that represents a
sufficient flow rate into and out of the cavity, and the movable membrane
portion is located in the third position when fluid in the cavity has a
third predefined fluid pressure greater than the second predefined fluid
pressure that represents that the rate of flow of fluid out of the cavity
is insufficient.

17. An indicator device for indicating the status of delivery of a bolus
of medical fluid flow through an infusion line to a patient, the
indicator device comprising:a housing surrounding a cavity through which
the fluid may flow, the housing having a fluid inlet adapted to be
coupled to a portion of the infusion line from which fluid would flow
into the housing, a fluid outlet adapted to be coupled to a portion of
the infusion line into which fluid would flow out of the housing, and an
indicator opening; anda flexible membrane disposed at the indicator
opening in contact with fluid in the cavity, the flexible membrane having
a moveable membrane portion configured to move in relation to the opening
in response to pressure of fluid in the cavity such that the moveable
membrane portion has a first position indicating a bolus is ready for
delivery and a second position when a bolus is not available for
delivery.

18. The indicator device of claim 17, further comprising:a check valve
located upstream of the cavity, the check valve configured to permit the
flow of fluid into the cavity and prevent the flow of fluid out of the
cavity.

19. The indicator device of claim 17, further comprising:a check valve
located downstream of the cavity, the check valve configured to permit
the flow of fluid out of the cavity and prevent the flow of fluid back
into the cavity.

20. The indicator device of claim 17, wherein said flexible membrane is
configured such that when the membrane is in the first position, pressing
the membrane into the cavity causes a bolus of fluid to flow from the
cavity out the fluid outlet.

Description:

BACKGROUND OF THE INVENTION

[0001]The invention is related generally to fluid delivery devices, and
more particularly, to a status indicator for indicating the status of the
flow of medical fluid through an administration device.

[0002]In the past, prolonged infusion of fluids has often been
accomplished using gravity flow methods, which typically involve the use
of intravenous administration sets and a bottle or bag of medical fluid
suspended above the patient. Such methods are cumbersome, imprecise, and
require bed confinement of the patient. Periodic monitoring of the
apparatus by the nurse or doctor is required to detect malfunctions of
the infusion apparatus.

[0003]The apparatus of the present invention can be used with minimal
professional assistance in an alternate health care environment, such as
the home. By way of example, devices of the invention can be comfortably
and conveniently removably affixed to the patient's body and can be used
for the continuous infusion of antibiotics, hormones, steroids, blood
clotting agents, analgesics, and other medicinal agents. Similarly, the
devices can be used for IV chemotherapy and can accurately deliver fluids
to the patient in precisely the correct quantities and rates over time.

[0004]The present invention is directed, generally, to an ambulatory drug
infusion pump for administering antibiotics, antiviral, and other IV
medications for critically ill patients and for home care or out-patient
applications.

[0005]In many situations, a patient may require multiple daily therapies,
intermittent infusion, or a slow and continuous introduction of
medicament liquid into the patient's system. Moreover, certain therapies
require medicament liquid or pharmaceutical solutions to be infused over
a particular period of time which may range anywhere from about 30
minutes to about several hours, for a therapeutic dose. It is therefore
very important that these medicament liquid or pharmaceutical solution
doses be administered completely and with a highly accurate introduction
rate (flow rate). Currently, a variety of devices exist that are able to
deliver medicament liquids and pharmaceutical solutions intravenously to
a patient. In the past few years, certain of these devices have offered
some degree or portability, but the most widely utilized of these devices
typically require a patient to be confined to a bed, thus limiting the
options available for patients who are able to be ambulatory.

[0006]So called ambulatory infusion pumps are gaining currency in medical
technology, given the trend towards shorter hospital stays and increasing
reliance on out-patient and home care treatment. Such ambulatory devices
typically function on an infusion pump delivery principle which pumps a
medicament liquid or other IV solution into the patient. The pressure
developed by the infusion pump is designed to overcome the resistance of
the patient's internal pressure and include regulators or restrictors in
the IV tubing set to attempt to control the rate of flow of the IV
solution into the patient. For example, it is common to pressurize a
container filled with a medicament liquid or IV solution by transmitting
a hydrostatic or gas pressure developed in an external or internal
gas-filled bladder to the IV solution container. By maintaining a
constant pressure in the bladder, it was hoped that the bladder would
exert (transmit) a constant pressure to the IV solution container,
thereby developing a constant flow rate of medicament liquid at the point
of infusion.

[0007]In the more common elastomeric-type infusion pump devices, the
elastomeric pumps use the pressure of an expanding elastomeric element to
push an IV solution through a rate controlling orifice or a constrictive
clamp. However, the flow rate of these systems are prone to several
external factors which are beyond the control of the device and are not
outwardly obvious to an uninitiated patient administering the infusion.

[0008]The reality with prior art systems is that ambulatory patients are
not readily able to determine the status of fluid flow in their infusion
system. Thus, patients tend to verify the status of their infusions by
disconnecting the pump from the catheter (i.e. break the line) to see if
drops form. This practice of breaking the line exposes the infusion line
to outside contaminants, creating an infection risk and potentially
putting the patient in contact with hazardous chemicals.

[0009]Hence, those skilled in the art have recognized a need for a flow
indicator device that is easily monitored by a home user to determine if
fluid is flowing in the administration line. Further, those skilled in
the art have recognized the need for an indicator device that can be used
to provide a bolus of medication to a patient. The present invention
fulfills these needs and others.

SUMMARY OF THE INVENTION

[0010]Briefly and in general terms, the present invention is directed to
an indicator device for indicating the status of medical fluid flow
through an infusion line, the indicator device comprising a housing
surrounding a cavity through which the fluid may flow, the housing having
a fluid inlet adapted to be coupled to a portion of the infusion line
from which fluid would flow into the housing, a fluid outlet adapted to
be coupled to a portion of the infusion line into which fluid would flow
out of the housing, and an indicator opening that provides fluid
communication with fluid residing in the cavity; and a flexible membrane
disposed at the indicator opening in contact with fluid in the cavity,
the membrane having a moveable membrane portion configured to move in
relation to the opening in response to pressure of fluid in the cavity
such that the movable membrane portion has a first position when fluid is
flowing through the cavity and a second position when fluid is not
flowing through the cavity, the first and second positions being
distinguishable either by visual and/or tactile means.

[0011]In more detailed aspects, the indicator device further comprises an
inlet flow restrictor disposed in the portion of the fluid line from
which the fluid flows into the cavity, the inlet flow restrictor
providing a first flow resistance to flow of medical fluid into the
cavity. The indicator device further comprises an outlet flow restrictor
disposed in the portion of the fluid line into which the fluid flows out
of the cavity, the outlet flow restrictor providing a second flow
resistance to flow of medical fluid out of the cavity. In a further
aspect, in one case the second flow resistance is greater than the first
flow resistance, and in another aspect the first flow resistance is
greater than the second flow resistance. In much further detail, the flow
restrictors are formed as part of the housing of the indicator.

[0012]In other aspects in accordance with the invention, the moveable
membrane portion is configured to recess into the cavity when the flow
rate of fluid through the cavity is at a first threshold, the moveable
membrane portion is configured to extend approximately level with the
opening of the housing when the flow rate of fluid through the cavity is
at a second threshold, and the moveable membrane portion is configured to
protrude outwardly from the opening of the housing when the flow rate of
fluid through the cavity is at a third threshold. The second threshold is
greater than the first threshold and the third threshold is greater than
both the first threshold and the second threshold.

[0013]In another aspect, the indicator device further comprises a position
indicator disposed on the moveable membrane portion, the position
indicator configured to provide a visual indication of the position of
the moveable portion in respect to the opening to more clearly visually
indicate the status of fluid flow through the fluid line.

[0014]In yet a further aspect, the movable membrane portion is configured
to have a first position, a second position, and a third position, such
that the moveable membrane portion is located in the first position when
fluid in the cavity has a first predefined fluid pressure that represents
that the flow rate of fluid into the cavity is insufficient, the movable
membrane portion is located in the second position when fluid in the
cavity has a second predefined fluid pressure greater than the first
predefined fluid pressure that represents a sufficient flow rate into and
out of the cavity, and the movable membrane portion is located in the
third position when fluid in the cavity has a third predefined fluid
pressure greater than the second predefined fluid pressure that
represents that the rate of flow of fluid out of the cavity is
insufficient. In more detailed aspects, the first predefined pressure is
about 0 kPa (0 psi), the second predefined pressure is about 24 kPa (3.5
psi), and the third predefined pressure is about greater than 48 kPa (7
psi).

[0015]In yet other aspects, the indicator device further comprises a check
valve located upstream of the cavity, the check valve configured to
permit the flow of fluid into the cavity and prevent the flow of fluid
out of the cavity. Further in accordance with another aspect, the
indicator device further comprises a check valve located downstream of
the cavity, the check valve configured to permit the flow of fluid out of
the cavity and prevent the flow of fluid into the cavity. And yet
further, the indicator device comprises a bolus device located at the
indicator opening in contact with the flexible membrane, and configured
such that pressing the bolus device into the cavity produces a bolus of
fluid from the cavity out the fluid outlet.

[0016]These and other aspects, features, and advantages of the present
invention will become apparent from the following detailed description of
the preferred embodiments which, taken in conjunction with the
accompanying drawings, illustrate by way of example the principles of the
invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]FIG. 1 depicts an elastomeric powered fluid pump in which is
contained medical fluid and a medical fluid administration set comprising
a conduit or fluid line that conducts the medical fluid from the supply
to a patient, and a fluid flow indicator device in accordance with
aspects of the invention in a fluid administration set.

[0019]FIG. 3A is a cross-sectional view of the fluid flow status indicator
device of FIG. 1 showing a housing, an inlet, a first fluid flow
restrictor at the inlet, an outlet, a second fluid flow restrictor at the
outlet, a cavity between the inlet and outlet, and a membrane in the
resting position showing insufficient or no fluid pressure through the
infusion line.

[0020]FIG. 3B is a cross-sectional view of the fluid flow status indicator
device of FIG. 1 showing a housing, an inlet, a first fluid flow
restrictor at the inlet, an outlet, a second fluid flow restrictor at the
outlet, a cavity between the inlet and outlet, and a membrane in the
normal position showing sufficient fluid pressure through the infusion
line.

[0021]FIG. 3C is a cross-sectional view of the fluid flow status indicator
device of FIG. 1 showing a housing, an inlet, a first fluid flow
restrictor at the inlet, an outlet, a second fluid flow restrictor at the
outlet, a cavity between the inlet and outlet, and a membrane in the
occluded position showing possible blockage downstream of the cavity.

[0022]FIG. 4 is a schematic diagram of a flow indicator and bolus
administration system in accordance with aspects of the invention showing
check valves, flow restrictors, and the flow indicator of FIG. 1.

[0023]FIG. 5 is a perspective view of an embodiment of the present
invention when used as a bolus device.

DETAILED DESCRIPTION OF THE INVENTION

[0024]The invention comprises a method and apparatus for indicating the
status of an infusion to a patient. In the following description,
numerous specific details are set forth in order to provide a more
thorough description of the present invention. It will be apparent,
however, to one skilled in the art, that the present invention may be
practiced without these specific details. In other instances, well-known
features have not been described in detail so as not to obscure the
invention.

[0025]In general, one or more embodiments of the invention comprise a
fluid flow indicator device coupled to an infusion line. The fluid flow
indicator comprises a fluid pressure chamber, a flexible (pressure
sensitive) elastomeric membrane attached to the chamber. Additionally, a
visually distinguishable or tactile device (e.g. a piece of plastic
material to provide indication of the position of the membrane by visual
inspection or by feel) may be attached in the vicinity of the center of
the membrane to further provide easy flow status cues to the patient or
care giver. Fluid flow restrictors may also be coupled on the upstream
and downstream ends of the indicator device to control pressure in the
chamber and to control the fluid flow rate through the chamber.
Preferably, the upstream restrictor provides less restriction than the
downstream restrictor.

[0026]The membrane in one or more embodiments of the indicator device is
configured to have a concave shape protruding into the pressure chamber
to indicate that the infusion has not been started or has been stopped or
ended (i.e. no pressure from the pressure source). As the infusion
progresses, the pressure in the chamber increases (to the source pressure
minus the upstream pressure drop) causing the membrane to deform into a
flat position. When the downstream line is occluded, the pressure in the
chamber increases to the source pressure causing the membrane to protrude
from the pressure chamber.

[0027]Embodiments of the present inventions would now be described with
reference to FIGS. 1-5. Referring now to the drawings in more detail in
which like reference numerals refer to like or corresponding devices
among the views, there is shown in FIG. 1 a fluid flow indicator device
20 in accordance with aspects of the invention located within a fluid
administration set used to deliver medical fluid to an ambulatory or home
patient 30. In particular, a fluid container or supply 10 taking one of
many forms, such as an elastomeric membrane-powered pump, bag, bottle, or
other pressurized container, is connected with the patient through a
conduit or tubing 40. The fluid conduit 40 conducts the fluid downstream
from the fluid supply to the indicator device 20 and then further
downstream to the patient. As used herein only for convenience and not
for a purpose of limitation, "upstream" shall refer to the direction
towards the supply 10, and "downstream" shall refer to the direction
towards the patient 30.

[0028]In accordance with aspects of the invention, a patient 30 or user of
the administration system of FIG. 1 can determine the status of the flow
of medical fluid through the line 40 by observing the indicator device
20. In particular, the status indicator device in FIG. 1 includes a
window or opening 21 in which a flow level membrane may be attached in
direct contact with fluid in the housing. The membrane is preferably
flexible and its position in relation to the opening is configured to
indicate to the user whether sufficient flow of medical fluid to the
patient is occurring or if there is a problem.

[0030]Referring now to FIGS. 3A-3C, a cross-sectional view of one
embodiment of status indicator 20 in accordance with aspects of the
invention is illustrated. The status indicator includes a housing 31, an
inlet port 32, a cavity 33, and an output port 34. An opening 35 permits
the patient, nurse, or other clinician to determine the status of fluid
flow through the status indictor device. In the opening, a flexible
membrane 36 may be disposed to move in the indicator device in accordance
with fluid pressure in the housing. In addition, a piece of material
acting as a position indicator 37 (e.g. a plastic indicator) may be
coupled to the membrane to provide easy visual feedback of the flow
status. Position indicator 37 may be configured to provide visual or
tactile cues of the flow status, for instance.

[0031]The flexible membrane 36 is mounted at the opening 35 and moves in
relation thereto to indicate the amount of pressure of the medical fluid
disposed within the cavity. As shown in FIG. 3A, the membrane is recessed
within the cavity away from the opening thereby indicating insufficient
pressure within the cavity. If the membrane were to be level with the
opening, as shown in FIG. 3B, the pressure of the medical fluid within
the cavity would be sufficient to accomplish the patient's infusion. If
the membrane protrudes outwardly from the opening of the housing, as
illustrated in FIG. 3C, the pressure within the cavity is too high thus
indicating that the downstream portion of the administration line may be
occluded. The flexible membrane may be configured with a protective shell
to prevent tampering.

[0032]In another embodiment of the present invention, the indictor could
be used as a bolus device for pain management. In this case the membrane
would have two states, concave (protruding into the pressure chamber)
which would indicate that no bolus is available and convex (protruding
out of the pressure chamber which would indicate that a bolus could be
delivered. In this configuration, the upstream restriction would be more
restrictive than the downstream restriction to ease delivery of the bolus
volume while allowing the bolus device to refill slowly. This prevents
the patient from administering several immediate bolus doses, as well as
permitting a constant flow of fluid while the bolus volume is refilled.
In addition, a check valve may be required on the pressure chamber input
to prevent backflow during bolus delivery.

[0033]FIG. 4 is a functional illustration of an embodiment of the present
invention when used as a bolus device. As illustrated, an upstream check
valve 50 is added between the Supply 10 and Restrictor 22 to prevent
backflow of fluid during bolus delivery. In addition, a downstream check
valve 60 may be required between Restrictor 26 and the patient to prevent
back flow of the bolus dose into the chamber.

[0034]FIG. 5 is a perspective view of an embodiment of the present
invention when used as a bolus device. As configured, check valve 50 is
coupled into housing 31 and the flexible membrane protrudes in a convex
form out of the pressure chamber when a bolus is ready to be delivered to
the patient. To deliver the bolus to the patient, the user depresses the
membrane thereby forcing the medical fluid to exit the chamber through
the Flow Out opening.

[0035]In summary, the embodiments presented and discussed above provide a
device that gives an indication of whether a given infusion with an
elastomeric infusion pump has started, is running, or is occluded. The
status indicator device comprises a fluid pressure cavity and a flexible
elastomeric membrane attached to the cavity. Additionally, a position
indicator (e.g. a plastic material) may be mounted on the membrane,
preferably in the vicinity of the center, to further provide feedback
(e.g. visual or tactile) of the position of the membrane. Fluid flow
restrictors are placed on the upstream and downstream ends of the status
indicator device in one embodiment to control pressure in the cavity and
to control the fluid flow rate. The device is provided with the membrane
in a concave shape, receding into the pressure cavity. This position
indicates that the infusion has not been started or has been stopped or
ended (no pressure from the pressure source). As the infusion progresses,
the pressure in the chamber increases causing the membrane to deform into
a flat position. When the downstream line is occluded, the pressure in
the chamber increases to the source pressure causing the membrane to
protrude outwardly from the pressure cavity. The plastic indicator would
improve differentiation of these various conditions. In an alternate
embodiment, the indicator could be used as a bolus device for the
purposes of pain management. In this embodiment, the indicator has two
states the first of which is concave, that indicates that no bolus is
available and the second of which is convex which indicates that a bolus
could be delivered.

[0036]Although the present invention has been described in terms of
certain embodiments, other embodiments that are apparent to those of
ordinary skill in the art are also within the scope of the invention. It
will be understood that the above described arrangements of apparatus and
the method therefrom are merely illustrative of applications of the
principles of this invention and many other embodiments and modifications
may be made without departing from the spirit and scope of the invention
as defined in the claims.